WASHINGTON (Yonhap) ― The Obama administration understands that there could be growing desire in Japan to go nuclear if the U.S. continues drastic budget cuts, a senior Pentagon official said Wednesday.

Christine Wormuth, deputy under secretary of defense for strategy, was responding to renewed worries over Japan’s handling of its huge plutonium stockpile for energy and research purposes amid the U.S. military’s budget constraints.

“Certainly, at the lowest levels I think there was an implicit understanding that the risks of that kind of proliferation, or the risks of countries that are scientifically capable enough to develop their own nuclear program, which certainly Japan is, would go up,” she said at a forum on Washington’s 2014 Quadrennial Defense Review, hosted by the Center for Strategic and International Studies.

She added, however, it “wasn’t an explicit factor.”

Plutonium can be turned into fissile material for nuclear weapons from fuel for nuclear power plants.

The U.S. recently asked Japan to give back more than 300 kilograms of mostly weapons-grade plutonium, which could be used to make up to 50 nuclear bombs, according to news reports.

Tokyo initially balked at the demand but later accepted it, they added.

China was quick to openly voice concerns about Japan’s nuclear program, raising the issue at a board session of the International Atomic Energy Agency earlier this month.

A U.S. diplomat dismissed such worries for now.

“We are not at all concerned that the plutonium is either being handled improperly or that there isn’t a plan for disposition,” Joseph Macmanus, U.S. ambassador to the IAEA, told reporters.

The Obama administration, seeking a “nuclear-free” world, has been active in a global nonproliferation drive.

It has refused to give advanced consent for South Korea to enrich uranium and reprocess spent fuel in their talks on revising civilian nuclear cooperation.

Meanwhile, the Pentagon official reaffirmed Washington’s commitment to the rebalance toward the Asia-Pacific region.

“Our alliance with Japan is very, very strong. We are committed to reassuring Japan and the region,” Wormuth said. “And our view is that there’s not a need for any kind of nuclear capability as long as our alliance remains strong, which we believe it is.”